Improving the Efficiency of Monitoring of Natural and Seeded Forage Grasslands in the Territories of Technogenic Pollution in the Non-Black Soil Zone of the Russian Federation

Abstract

The data of impact radiological monitoring in the bottomland meadows of the Desna and Iput’ rivers within the Bryansk District (the Non-Black Soil Zone of the Russian Federation) have been presented and discussed; the dynamics of the specific activity of caesium in the grass stand has been assessed according to the floristic composition of communities and the shoot height as well. For the first time the data on accumulation of radionuclides have been estimated with no regard for certain types of grass stand: meadow communities have been examined as a whole; a phyto-row has been constructed. The indices have been identified of the specific activity of caesium in herbage components in the Post-Chernobyl period and when taking melioration measures, using a synthetic ameliorant: amorphous silicon dioxide. All meadows have been proved to be the source of high-quality nutritious forage, pastures. Distribution of the examined ¹³⁷Cs radionuclide over the shoot height is uneven: it is recorded that its maximum content is in the horizon of up to 5cm, and minimum – in the upper shoot parts and inflorescences. ¹³⁷Cs is accumulated in herbage of meadow plant associations in descending order as follows: Glycerietum maximae Nowiński 1930 (Scirpetum sylvatici Ralski 1931) > Agrostio stoloniferae–Beckmannietum eruciformis Alexandrova 1989 > Phalaridetum arundinaceae Libbert 1931> Anthoxantho–Agrostietum tenuis Sill. 1933 em. Jurko 1969 (Lysimachio vulgaris–Filipenduletum ulmariae Balátová-Tuláčková 1978, Deschampsio–Agrostietum tenuis Sill. 1933 em. Jurko 1969) > Poo palustris–Alopecuretum pratensis Shelyag-Sosonko et al. 1987 > Fillpendulo ulmariae–Festucetum rubrae Bulokhov 1990 (Heracleo sibirici-Alopecuretum pratensis Bulokhov 1990). Maximum accumulation capability is inherent in meadow communities with high soil moisture, low nitrogen and pH indices (according to G. Ellenberg, 1992). Experimental amelioration measures have been taken on natural meadows involved in pasture rotation, with the “Kovelos-Rost” synthetic preparation being introduced as a top-dressing. It has been found that agrochemical measures definitely reduce accumulation of radionucleotide in the plant biomass (over the shoot height): all accumulation coefficients indicate that there is no accumulation of ¹³⁷Cs. Minimum accumulation coefficient is 0.25, maximum – 0.97. The protective effect of amorphous silicon dioxide is determined by chemical properties of hydrogenated silicon: its presence increases the solution acidity; caesium radionuclide becomes inactive and is poorly absorbed by herbage.